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1.
Sensors (Basel) ; 21(16)2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34450980

RESUMO

Copper (II) ions have been shown to greatly improve the chemical stability and peroxidase-like activity of gold nanoclusters (AuNCs). Since the affinity between Cu2+ and pyrophosphate (PPi) is higher than that between Cu2+ and AuNCs, the catalytic activity of AuNCs-Cu2+ decreases with the introduction of PPi. Based on this principle, a new colorimetric detection method of PPi with high sensitivity and selectivity was developed by using AuNCs-Cu2+ as a probe. Under optimized conditions, the detection limit of PPi was 0.49 nM with a linear range of 0.51 to 30,000 nM. The sensitivity of the method was three orders of magnitude higher than that of a fluorescence method using AuNCs-Cu2+ as the probe. Finally, the AuNCs-Cu2+ system was successfully applied to directly determine the concentration of PPi in human urine samples.


Assuntos
Ouro , Nanopartículas Metálicas , Colorimetria , Cobre , Difosfatos , Corantes Fluorescentes , Humanos , Limite de Detecção , Peroxidase , Peroxidases , Espectrometria de Fluorescência
2.
Chemistry ; 2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33913575

RESUMO

In an effort to combine the favorable catalytic properties of Co3 O4 and CeO2 , nanocomposites with different phase distribution and Co3 O4 loading were prepared and employed for CO oxidation. Synthesizing Co3 O4 -modified CeO2 via three different sol-gel based routes, each with 10.4 wt % Co3 O4 loading, yielded three different nanocomposite morphologies: CeO2 -supported Co3 O4 layers, intermixed oxides, and homogeneously dispersed Co. The reactivity of the resulting surface oxygen species towards CO were examined by temperature programmed reduction (CO-TPR) and flow reactor kinetic tests. The first morphology exhibited the best performance due to its active Co3 O4 surface layer, reducing the light-off temperature of CeO2 by about 200 °C. In contrast, intermixed oxides and Co-doped CeO2 suffered from lower dispersion and organic residues, respectively. The performance of Co3 O4 -CeO2 nanocomposites was optimized by varying the Co3 O4 loading, characterized by X-ray diffraction (XRD) and N2 sorption (BET). The 16-65 wt % Co3 O4 -CeO2 catalysts approached the conversion of 1 wt % Pt/CeO2 , rendering them interesting candidates for low-temperature CO oxidation.

3.
Mol Ecol Resour ; 21(4): 1243-1255, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33421343

RESUMO

Chinese mahogany (Toona sinensis) is a woody plant that is widely cultivated in China and Malaysia. Toona sinensis is important economically, including as a nutritious food source, as material for traditional Chinese medicine and as a high-quality hardwood. However, the absence of a reference genome has hindered in-depth molecular and evolutionary studies of this plant. In this study, we report a high-quality T. sinensis genome assembly, with scaffolds anchored to 28 chromosomes and a total assembled length of 596 Mb (contig N50 = 1.5 Mb and scaffold N50 = 21.5 Mb). A total of 34,345 genes were predicted in the genome after homology-based and de novo annotation analyses. Evolutionary analysis showed that the genomes of T. sinensis and Populus trichocarpa diverged ~99.1-103.1 million years ago, and the T. sinensis genome underwent a recent genome-wide duplication event at ~7.8 million years and one more ancient whole genome duplication event at ~71.5 million years. These results provide a high-quality chromosome-level reference genome for T. sinensis and confirm its evolutionary position at the genomic level. Such information will offer genomic resources to study the molecular mechanism of terpenoid biosynthesis and the formation of flavour compounds, which will further facilitate its molecular breeding. As the first chromosome-level genome assembled in the family Meliaceae, it will provide unique insights into the evolution of members of the Meliaceae.


Assuntos
Genoma de Planta , Meliaceae , Toona , China , Cromossomos de Plantas , Malásia , Filogenia , Toona/genética
4.
J Colloid Interface Sci ; 573: 78-86, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32259694

RESUMO

Inorganic p-type materials show great potential as the hole transport layer in perovskite solar cells with the merits of low costs and enhanced chemical stability. As a p-type material, cobalt oxide (CoO) has received so far not that level of attention despite its high hole mobility. Herein, solution-processed p-type CoO nanocrystalline films are developed for inverted mixed perovskite solar cells. The ultrafine CoO nanocrystals are synthesized via an oil phase method, which are subsequently treated by a ligand exchange process using pyridine solvent to remove the long alkyl chains covering the nanocrystals. From this homogeneous colloidal solution CoO films are obtained, which exhibit a smooth and pin-hole free surface morphology with high transparency and good conductivity. The ultraviolet photoelectron spectrum also indicates that the energy levels of the CoO film match well with the mixed perovskite Cs0.05(FA0.83MA0.17)0.95(I0.83Br0.17)3. Inverted solar cells based on crystalline CoO films with ligand exchange show a reasonable energy conversion efficiency, whereas devices based on CoO films without ligand exchange suffer from a strong S-shape JV-characteristic. Thus, the crystalline CoO films are foreseen to pave a new way of inorganic hole transport materials in the fields of perovskite solar cells.

5.
Dalton Trans ; 48(28): 10448-10454, 2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31231748

RESUMO

BiSbS3@N-doped carbon (NC) core-shell nanorods were prepared through a simple preparation process. As anode materials for sodium-ion batteries (SIBs), BiSbS3@NC core-shell nanorods present excellent electrochemical performance with higher specific capacity and better rate capability compared with the unmodified pristine BiSbS3 nanorods. The BiSbS3@NC electrode delivers high sodium storage capacity (771.5 mA h g-1 in the 2nd cycle) and excellent rate performance (capacity of 518.4 mA h g-1 at 1000 mA g-1). The improvement in electrochemical performance results from the coated conductive NC layer which brings about fast ion/electron transfer and buffers volume expansion. The BiSbS3@NC core-shell nanorods are thus promising high performance anode materials for SIBs.

6.
Mikrochim Acta ; 186(5): 271, 2019 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-30963315

RESUMO

A method is described for the preparation of copper(II)-modified keratin-capped gold nanoclusters (AuNCs) with adjustable Au/Cu molar ratio through a two-step synthetic route. The introduction of Cu(II) is known to cause quenching of the fluorescence of such AuNCs. It is found, however, that the Cu(II) loaded AuNC (AuNC-Cu2+) display strongly enhanced peroxidase-like activity and improved chemical stability. This is assumed to be due to the synergistic effect of the gold and copper atoms and in contrast to the single components (pure AuNCs and copper ions). The kinetic parameters of the new peroxidase mimic show a higher Kcat value (12.1 × 10-4 s-1) and a lower Km value (53 µM) for H2O2 (compared to those of conventional AuNCs). The catalytic activity is stable and remains essentially unchanged after two months. The interactions of AuNCs with Cu(II) were characterized by fluorescence spectroscopy, UV-vis spectroscopy and X-ray photoelectron spectroscopy. Based on these findings, a glucose colorimetric assay at 452 nm was developed that has a detection range from 1.6 to 800 µM and a 0.26 µM detection limit. Graphical abstract Copper ion-modified keratin-capped gold nanoclusters (AuNC-Cu2+) exhibit enhanced peroxidase-like activity owing to the synergistic effect of the gold and copper atoms which is in contrast to pure AuNCs.


Assuntos
Materiais Biomiméticos/química , Colorimetria/métodos , Cobre/química , Glucose/análise , Ouro/química , Queratinas/química , Peroxidase/metabolismo , Humanos , Cinética , Limite de Detecção , Nanopartículas Metálicas/química
7.
Acta Physiol Plant ; 41(7): 126, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-32214546

RESUMO

Toona sinensis is a deciduous tree native to eastern and southeastern Asia that has important culinary and cultural values. To expand current knowledge of the transcriptome and functional genomics in this species, a de novo transcriptome sequence analysis of young and mature leaf tissues of T. sinensis was performed using the Illumina platform. Over 8.1 Gb of data were generated, assembled into 64,541 unigenes, and annotated with known biological functions. Proteins involved in primary metabolite biosynthesis were identified based on similarities to known proteins, including some related to biosynthesis of carbohydrates, amino acids, lipids, and energy. Analysis of unigenes differentially expressed between young and mature leaves (transcriptomic libraries 'YL' and 'ML', respectively) showed that the KEGG pathways of phenylpropanoid, naringenin, lignin, cutin, suberin, and wax biosynthesis were significantly enriched in mature leaves. These results not only expand knowledge of transcriptome characteristics for this valuable species, but also provide a useful transcriptomic dataset to accelerate the researches on its metabolic mechanisms and functional genomics. This study can also further the understanding of unique aromatic metabolism and Chinese medicinal properties of T. sinensis.

8.
Beilstein J Nanotechnol ; 7: 1815-1821, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28144531

RESUMO

Raman and IR investigations indicated the presence of reduced graphene oxide (rGO)-like residues on ceria nanoparticles after solvothermal treatment in ethanol. The appearance of such structures is closely related to cerium tert-butoxide as precursor and ethanol as solvothermal solvent. The rGO-like residues improve the catalytic CO oxidation activity. This was also confirmed by introduction of "external" graphene oxide during sol-gel processing, by which the rGO structures and the catalytic activity were enhanced.

9.
Chemistry ; 21(2): 885-92, 2015 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-25384333

RESUMO

Co3 O4 -modified CeO2 (Co/Ce 1:4) was prepared by a combination of sol-gel processing and solvothermal treatment. The distribution of Co was controlled by means of the synthesis protocol to yield three different morphologies, namely, Co3 O4 nanoparticles located on the surface of CeO2 particles, coexistent Co3 O4 and CeO2 nanoparticles, or Co oxide structures homogeneously distributed within CeO2 . The effect of the different morphologies on the properties of Co3 O4 -CeO2 was investigated with regard to the crystallite phase(s), particle size, surface area, and catalytic activity for CO oxidation. The material with Co3 O4 nanoparticles finely dispersed on the surface of CeO2 particles had the highest catalytic activity.

10.
Catal Letters ; 144(3): 403-412, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24532959

RESUMO

ABSTRACT: CeO2 was synthesized by combined sol-gel and solvothermal processing of gels obtained from acetaldoximate-modified cerium(IV) t-butoxide in the presence of the non-ionic surfactant Pluronic F127. The use of cerium(IV) t-butoxide as precursor contrasts very favorably with the often used ceric ammonium nitrate and results in more reliable and tailorable properties of the final materials. The kind of post-synthesis treatment of the gels and the composition of the precursor mixture proved to be crucial for obtaining high surface area ceria with a high Ce3+ proportion. Calcination in air or under nitrogen was compared with solvothermal treatment in ethanol or water and a combination of solvothermal treatment and calcination. The obtained materials are composed of 3.5-5.5 nm ceria nanoparticles. The highest specific surface area of 277 m2/g was obtained after solvothermal treatment, and 180 m2/g when solvothermal treatment was followed by calcination in air to remove residual organic groups. The highest Ce3+ proportion was 18 % after solvothermal treatment in ethanol and additional calcination in air. CO oxidation on selected samples indicated that activity scaled with surface area and thus was largest for samples solvothermally treated in ethanol. The reaction rate of the best sample was about 75-times larger than that of commercial ceria. GRAPHICAL ABSTRACT: .

11.
Eur J Inorg Chem ; 2012(27): 4294-4300, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24899867

RESUMO

Zinc(II) complexes with dangling functional organic groups were synthesized by reaction of zinc acetate with a series of bifunctional p-substituted benzene derivatives (a combination of carboxylate, oximate, amino, ß-ketoimine, and salicylaldime groups). Selective coordination to carboxylate groups was observed when the second functional group was an oxime or ß-ketoimine group. When the second group was an amine or salicylaldimine moiety, these groups were additionally coordinated. From the reaction with p-aminobenzoic acid, the compound [Zn2(OOCCH3)(OOC-C6H4-NH2)3]∞ was crystallized. It is a three-dimensional coordination polymer with bridging aminobenzoate ligands.

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